Diaphragm construction for thermostats or motors



Nov. 16, 1954 w. M. DILLON 2,694,415

DIAPHRAGM CONSTRUCTION FOR THERMOSTATS OR MOTORS Filed D60. 23, 1950 2Q 2&4

Z Jende///ZZfl/// H Q 16 971M441 7*W Hiya/7790" 2,694,415 Patented ,Nov. .116, v195.4

DIAPHRAGM CONSTRUCTIONFORiTHERMO- STA-TS -R=MOTORS Wendell M. Dillon, .Lawrence, Mass.,:1assignorr.to Watts Regulator Company, .Lawrence,'Mass.,-za corporation of Massachusetts ApplicationDecemher'23, 1950, Serial No.-202;510

1 Claim. "((315137792) The: present invention relatessto a -ithermostatror motor .for use in connection -'witht.the -operation of "valves, -con- .trols, and other appliances.

The device of thevpresent invention-is included in that. generalclass. of thermostats ori motors having alhous- .ing, :-a work plunger orpiston' slidable in the'housing, an expansible materialfor .actuating the piston, vand :a hexible. diaphragm interposed between the piston and the expansible material. The diaphragmdsforthe purpose .of preventing the expansible material .from seeping out .of the housing around the piston and providesaa flexible :seal which will containthe expan'sible materialsubstantially within the housing butv upon expansiontofkthe ma- 'terial will permit linear movement-of .therpiston.

In most previous devicesof the general character. above referred to and. in .whicha flexible .diaphragm .was'employed, the diaphragm was substantially fiat and the plunger Thad a fiat or. rounded end. ILfind withdsuch 3 previous devices that there are certain undesirable features in performance; principally the deformation of the diaphragm which does not give a positive setting of the valve or otherdevice controlled by the wo'rk plunger or piston. previous devices produces a greaterdeformation-of the diaphragm which means that thereimust be expansion of the expansible .materialacting on the diaphragm through :a .greaterznumber of degrees before the work plunger reaches the samepositionso that the valve wouldnot always operate at the sametemperature and-"this variable A change in loadingon theplunger in these would be due to conditions in the thermostat or: motor construction resulting -in variations-in pressure which would afiect the :net loading on-the'workplunger. An object "thereforeof the present invention is to eliminate these defects 'bymeansof a contoured-diaphragm and alface on the work plunger which is-contoured -to"be .compatible with the contoured diaphragm.

'Another object is the provision of a thermostat'or mo-' tor of the general. nature referred-to, in-which the contouring of'thediaphragm consists of providing acen- 'traldepressed or looped portionsurrounded by an an- :nular reversecurved portion terminating in a substantially fiat sealing flange to be confinedbetween a housing for expansible material and a. guide sleeve for the work plunger.

Still another'object of the rinventionhis the provision of a thermostat or motor of the above nature in which the "end of the Work plunger next "to .the diaphragm 'is' contoured in a somewhat similarmanner, that :isgprovided with a central 'convexly rounded portion and .an annular concave portion surroundingi the central "'portion and terminating'ina'substantiallyflat plane'at' the periphery of thejplunger.

A further object is the provision of a thermostator .motor. of vthe above character in'whichthe workplunger is effectively sealedby'meansof aiboot surrounding the workplunger'and having an enlarged portion surrounding the adjacent portion of the plunger housing to prevent damage to the work plunger and exclude dirt or other foreign matter from entering between the plunger and the housing.

With these and other objects in view,

Figure l is a longitudinal sectional view of a thermostat embodying the present invention and showing the piston prior to being loaded as with a spring loaded valve or the like;

Figure 2 is a view similar to Figure 1 but showing a modification in which a cell of expansible material is set -apart ;:from :ithe swalste, rFigure 51, showiu'g ithe cell :next

valve or. other :device controlled :by .thez plungerp and Figure .4: is 'asimilar dview ShOWlng th6" PaftS lilluOP- erative -position, that:is,=: whenz-expansionahasltaken place and .moved tthezrplun'gerrto perform. a valve iopening ot 10 closing operation or :the like.

Referring in ;detail. to.= thea drawingsathe adevice includes a. housing .10 whicha in':theapreierred form isacylindrical andhas an.open-.upperi end. alt will :bezunderstood that the device can .be used ain anyrposition i butnforxpurposes of convenience ..in .the present zldescriptionzthe "open end will be referred to: astthe :uppercend. 'flThetopposite tor lower end :of thenhousingidllais fof: 'c-losedmonstruction. The plug .12 is .used toi seal:theihousingiafter ituzisnfilled with a suitable expansible smaterial =35.

The numeral .20 refersgenerally to 2a,tpiston or-wvork plunger. slidableinaa-isleeve torzguidezelement 18 forming an extension ofthe upperxrendofvtheahousingulO. The

sleeve 18 has an outwardly extending mountinglfiange 16 and the'housing :10-1hasjan .annular iflange 1.4: to stirround it. The. .upper en'diiofithe'zfiangeel4'iis.:inturned as at 22 to :hold':the-partstassembled, iaudiaphra-gm. -28 ibeing interposed between theitwo. .Thepiston' isaadapted to be connectedr'with a=switch, .valve.ior otherscontroL-as will be readilyiunderstood.

The lower end .of-itheipiston presents a" contoured surface having a rounded or convexl'centralapartindicated at 24 and a peripherala part1 26:forming .aconcave :ring around the centrallpa'rt. 'sTheipistoni substantially spans the internal. diameter of. the sleeve 18,1 bein'g ltpre'ferably aiworkingiorslidingt fitith'erein.

The'numeral-ZS indicates'igenerallyta diaphragm which preferably .is composed 10f frubber or La" rubber: product such as butyl rubher-aszit is:substantially:non-permeable. The diaphragm .28 aincludessan'iouter flange portion. 30 which istprovided'twit'h. a bea'cli33: touseatrin an annular groove 34. of the housingz10:.to :therebyffirmly: anchorthe diaphragm with respect to the housing and the sleevealS when the upper marginal- 'edgeof the fian'geia'l t'istturned from the dotted'original shape inwardly as at'fi22.

Since the diaphragmiZS isiprefera'bly ofzrubber'or rubber product, it .is 1 of courser'stretchable iand yieldable land it is likewise'deformable. Itisiunderstoodzthat otherrmaterialszhavethe same general 'iphysi'calreharacteristicsxas above specificallyreferred :to.

The expansible m'aterial 35 is "inserted in'Fthe housing 10 filling. the latter :u :to' therdiaphragmi 28'1aftertwhich the lower end .of 'the :hou'singis closed 5 by wthe iclosure plug 12 which is secured inplaceibylany' preferred-methodsuch as by welding. In"the-completed .unit, air is removed by suitable meansi so Ithat iwithin'ithe operating range the housing'is completely filled'with"thetexpansible material. Thez expansible material :mayfiberof any numerous preferred "forms such I as wax, "crystalline material, etc. Whatever 'thetmaterial: 35rused'. is, -'itis1subject to expansion" application: ofiheat 'theretoxand. is "subject to contraction upon: cooling.

The diaphragm 28..is preformedbefore assembly between the sleeve18 and' the housingltl"and-particularly the partition element 3132 thereof isipreformed. The partition element in .its 'normal :condition, ras iillustrated in Figures. 1 and :2, has 1 the loope'd portion 31 at 'its -center depending' sbelow ithe zuppermost :extremities'ithereof, and 'has lthe" annular reversely 'cUrvedtpartJiaZ. :Therpan tition element:- thus 'ha's-sa 'i surfacetarea t gre'aterflthan".: the cross-sectional: area of: the housing whereby thei artition element can be flexed and deformed and moved from one position to another without stretching. The exact shape of the partition element as illustrated in Figure 1 is of course only a drafting representation and it is impossible to accurately illustrate any one of its numerous intermediate positions.

In order to exclude dirt and other foreign material from between the guide sleeve 18 and the work plunger 20, I provide a boot 36 of rubber-like material having an enlarger portion 37. The portion 36 is snugly fitted around the plunger 20 and the portion 37 is snugly fitted around the sleeve 18. Accordingly, the plunger can move the required amountfor valve actuation with respect to the sleeve and the portions 36 and 37 will be stretched or distorted to some extent but the seal at this point will remain intact.

The diaphragm 28 and the' lower end of the plunger are contoured as described and as .shown in Figures 1 and 2 so that the parts are in the position illustrated when there is no load on the plunger. Accordingly, when a. load is applied such as the spring load of a valve, the

plunger is forced downwardly until it contacts the diaphragm substantially its entire diameter inside its contact with the flange 16 of the sleeve 18 as in Figure 3. It is obvious that when the parts are thus in the loaded position, deformation of the diaphragm when the expansible material 35 expands due to temperature rise and moves the parts for instance to the position shown in Figure 4. Since the rubber 31 is incompressible and air spaces have there is substantially no space left for any:

been minimized due to the contouring of the diaphragm;

work plunger 20 is connected to the valve or other ap-,

pliance being operated in such a way that the load of the appliance is exerted on the plunger which forces it downwardly to the position of Figure 3. Upon expansion of the expansible material 35, the plunger then moves in the desired proportional relationship to the expansion of the material.

The diaphragm 28 remains in the loaded position of Figure 3 the same as in the unloaded position of Figure l. The plunger, however, moves downwardly under the force of the load to minimize the air space between the diaphragm and the plunger so that upon operation of the appliance resulting from expansion of the material 35, an accurate movement-to-expansion relationship is had. The looped character of the diaphragm 28 contoured as disclosed and the contouring of the plunger compatible therewith are important contributions to this result.

My thermostat or motor is readily adaptable as in Figure 1 for controlling a valve or the like in response to temperature adjacent the valve or from a remote point as disclosed in Figure 2. housing is indicated as 10a and there is a bulb or cell 10b remote therefrom, the two being connected by a conduit 10c and the expansible material 350 then filling all three of the elements just enumerated. In an installation of this kind, material such as those in the alcohol groups are suitable depending upon the particular installation and the temperatures encountered.

In the interpretation of the claims herein, it is intended that the expression expansible material encompasses not only the material indicated at 35 which is actually expansible but the liquid 35a which may not be operative in response to expansion as such but rather in response to flowing into the article and being thereby effectively expansible. For instance, in place of the bulb 1012 a piston-cylinder arrangement might be provided for mechanically displacing fluid through the conduit 10c into the housing 10a and being thereby effectively expansible in the housing 10a.

The partition element 28 can 'be'moved in response to expansion of the expansible material 35 from the position shown in Figure 3 to the position shown in Figure 4 without stretching the partition element, that is, the partition element possesses suflicient surface area that can be folded, looped, or deformed. In the deformation In said Figure 2 the of the partition element it is not stretched but is unfolded" in a manner similar to a bellows. The eflect -is that when the piston is in retracted position the partition element 28 assumes the position in which it occupies an area less than its full extended area and when it is expanded or extended, it assumes an actual area that is greater than its effective area in collapsed or retracted position. Thus, there is no stress on the partition element 28. The diaphragm 28 thus not only serves the previously known purpose of preventing the expansible material frorn seeping out around the piston but also the diaphragm is such that a true movement-to-pressure or temperature ratio is had.

The device illustrated in Figure l is what is known as a thermostat, that is, it operates in response to changes in temperature. However, it is contemplated that the device may be employed as a motor such as illustrated in Figure 2. The construction of the device is the same as in Figure 1 except that instead of a single closed housing, a housing is employed having a tubular portion 10c for connection with a source of fluid such as a cell 10b. Instead of employing an expansible material, the fluid 35a is flowed bodily into the interior of the housing 10a and therefore the device would not operate as a thermostat but as a motor. In the interpretation of the claim herein it is intended that the expression expansible material encompasses not only the material 35 which is actually expansible but the liquid 35a which may not be operative in response to expansion as such, but rather in response to flowing into the housing 10a and being thereby effectively expansible.

While I have herein shown and described certain embodiments of my invention, it will be understood of course that I do not wish to be limited thereto since many modifications may be made, and I therefore contemplate by the appended claim to cover any such modification or substitution of mechanical equivalents as fall within the true spirit and scope of my invention.

I claim:

In a'construction of the character disclosed; a two part housing, each part having a cylindrical bore of constant diameter registering with the bore of the other part; a work plunger having a diameter substantially the same as the bore and slidably received in the bore and having its end in the form of a shallow convex dome; a flexible diaphragm of substantial thickness extending across the bore having a central looped portion seated against the entire face of the dome and sandwiched between the parts at its entire area outboard the central looped portion; and expansible material disposed in the housing on the side of the diaphragm opposite the work plunger whereby the diaphragm is sandwiched at its central looped portion between the plunger and the expansible material and at all other portions by the parts of the housing and whereby the plunger has limited movement between a'lower position wherein the edge of the dome is flush with the lower edge of the upper section and an upper position wherein the plunger is above the lower edge of the upper section by a distance less than the thickness of the diaphragm.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,034,538 Schnell Mar. 17, 1936 2,178,953 Chilton Nov. 7, 1939 2,264,413 Siegerist Dec. 2, 1941 2,489,769 Flick n Nov. 29, 1949 FOREIGN PATENTS Number Country Date 10,607 Great Britain Mar. 17, 1936 531,280 Great Britain Jan. 1, 1941 

